The invention relates to a system comprising a first coding section for coding a first digital signal into a second digital signal and comprising a second coding section for decoding the second digital signal into a third digital signal, the first coding section and the second coding section being coupled via a transmission channel, the first coding section comprising
a first arrangement being provided with PA1 a first coding apparatus being provided with PA1 a second arrangement being provided with PA1 the second coding apparatus being provided with PA1 the first coding section and the second coding section each being provided with PA1 memory means comprising at least a first memory field and a second memory field for storing in the first memory field at least PA1 processor means coupled to the memory means for adapting the information in response to a further received symbol. PA1 combining means for combining at least two probability signals into a first combination signal, the first information being a function of this first combination signal, and for combining at least two probability signals into a second combination signal, the third information being a function of this second combination signal, and for combining at least two probability signals into a third combination signal, and PA1 converting means for converting the third combination signal into at least one probability signal. PA1 a first arrangement being provided with PA1 a first coding apparatus being provided with PA1 memory means comprising at least a first memory field and a second memory field for storing in the first memory field at least PA1 processor means coupled to the memory means for adapting the information in response to a further received symbol. PA1 combining means for combining at least two probability signals into a first combination signal, the first information being a function of this first combination signal, and for combining at least two probability signals into a second combination signal, the third information being a function of this second combination signal, and for combining at least two probability signals into a third combination signal, and PA1 converting means for converting the third combination signal into at least one probability signal. PA1 an input for receiving a first digital signal comprising a number of symbols, PA1 an output for generating a fourth digital signal comprising at least one probability signal, PA1 memory means comprising at least a first memory field and a second memory field for storing in the first memory field at least PA1 processor means coupled to the memory means for adapting the information in response to a further received symbol. PA1 combining means for combining at least two probability signals into a first combination signal, the first information being a function of this first combination signal, and for combining at least two probability signals into a second combination signal, the third information being a function of this second combination signal. PA1 a first input for receiving a first digital signal comprising a number of symbols, PA1 a second input for receiving a fourth digital signal comprising at least one probability signal and originating from an arrangement, and PA1 an output for generating a second digital signal. PA1 converting means for converting the third combination signal into at least one probability signal. PA1 receiving the first digital signal comprising a number of symbols, PA1 generating, in response to the first digital signal, a fourth digital signal comprising at least one probability signal, PA1 coding the first digital signal into the second digital signal by using the fourth digital signal, PA1 generating, in response to the third digital signal, a fifth digital signal comprising at least one probability signal, PA1 decoding the second digital signal into the third digital signal by using the fifth digital signal, PA1 storing in a first memory field at least first information relating to at least two probability signals, and second information relating to at least a first number of symbols having a first value and a second number of symbols having a second value, PA1 storing in a second memory field at least third information relating to at least two probability signals, and fourth information relating to at least a third number of symbols having a first value and a fourth number of symbols having a second value, and PA1 adapting the information in response to a further received symbol. PA1 combining at least two probability signals into a first combination signal, the first information being a function of this first combination signal, PA1 combining at least two probability signals into a second combination signal, the third information being a function of this second combination signal, PA1 combining at least two probability signals into a third combination signal, and PA1 converting the third combination signal into at least one probability signal.
an input for receiving the first digital signal comprising a number of symbols, PA2 an output for generating a fourth digital signal comprising at least one probability signal, PA2 a first input for receiving the first digital signal comprising said number of symbols, PA2 a second input for receiving the fourth digital signal originating from the first arrangement, and PA2 an output for generating the second digital signal, and the second coding section comprising PA2 an input for receiving the third digital signal comprising a number of symbols and originating from a second coding apparatus, PA2 an output for generating a fifth digital signal comprising at least one probability signal, PA2 a first input for receiving the second digital signal originating from the first coding apparatus, PA2 a second input for receiving the fifth digital signal originating from the second arrangement, and PA2 an output for generating the third digital signal comprising said number of symbols, PA2 first information relating to at least two probability signals, and PA2 second information relating to at least a first number of symbols having a first value and a second number of symbols having a second value, and for storing in the second memory field at least PA2 third information relating to at least two probability signals, and PA2 fourth information relating to at least a third number of symbols having a first value and a fourth number of symbols having a second value, and PA2 an input for receiving the first digital signal comprising a number of symbols, PA2 an output for generating a fourth digital signal comprising at least one probability signal, PA2 a first input for receiving the first digital signal comprising said number of symbols, PA2 a second input for receiving the fourth digital signal originating from the first arrangement, and PA2 an output for generating the second digital signal, the coding section being provided with PA2 first information relating to at least two probability signals, and PA2 second information relating to at least a first number of symbols having a first value and a second number of symbols having a second value, and for storing in the second memory field at least PA2 third information relating to at least two probability signals, and PA2 fourth information relating to at least a third number of symbols having a first value and a fourth number of symbols having a second value, and PA2 first information relating to at least two probability signals, and PA2 second information relating to at least a first number of symbols having a first value and a second number of symbols having a second value, and for storing in the second memory field at least PA2 third information relating to at least two probability signals, and PA2 fourth information relating to at least a third number of symbols having a first value and a fourth number of symbols having a second value, and
Such a system is known from U.S. Pat. No. 5,023,611, which discloses the first coding section (encoder 101 in FIG. 1 of U.S. Pat. No. 5,023,611) comprising the first arrangement (context extractor 105 and probability estimator 106 in FIG. 1 of U.S. Pat. No. 5,023,611) and the first coding apparatus (entropy encoder unit 104 in FIG. 1 of U.S. Pat. No. 5,023,611), and which discloses the second coding section (decoder 103 in FIG. 1 of U.S. Pat. No. 5,023,611) comprising the second arrangement (context extractor 110 and probability estimator 111 in FIG. 1 of U.S. Pat. No. 5,023,611) and the second coding apparatus (entropy decoder unit 109 in FIG. 1 of U.S. Pat. No. 5,023,611). Both coding sections are coupled via a transmission channel (transmission media 102 in FIG. 1 of U.S. Pat. No. 5,023,611), and each comprise processor means (context extractor 105 comprises a computer or a digital signal processor as disclosed in column 3 lines 21-26 of U.S. Pat. No. 5,023,611, and context extractor 110 is identical to context extractor 105 as disclosed in column 7 lines 61-66 of U.S. Pat. No. 5,023,611). Such processor means will always be coupled to memory means which, as disclosed in IEEE Transactions on INFORMATION THEORY, May 1995, Volume 41, Number 3, in particular "The Context-Tree Weighting Method: Basic Properties", by F. M. J. Willems, Y. M. Shtarkov and T. J. Tjalkens, pages 653-664, will comprise at least a first memory field and a second memory field for storing in the first memory field at least first information relating to at least two probability signals (P.sub.e (a.sub.s,b.sub.s) and P.sub.w.sup.s as disclosed on page 659 of the IEEE article) and second information relating to at least a first number of symbols having a first value and a second number of symbols having a second value and for storing in the second memory field at least third information relating to at least two probability signals and fourth information relating to at least a third number of symbols having a first value and a fourth number of symbols having a second value. In response to a further received symbol, the processor means adapt said information.
Such a system is disadvantageous because it needs a giant memory capacity inside the first arrangement as well as inside the second arrangement.